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Document aeios.AES.rekey() and refactor arg validation #7684

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Merged
merged 3 commits into from
Mar 8, 2023
Merged

Document aeios.AES.rekey() and refactor arg validation #7684

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9015592
Document aeios.AES.rekey() and refactor arg validation
isacben Mar 5, 2023
8955caf
Fix capitalization of the IV argument (documentation)
isacben Mar 6, 2023
b7db289
Second fix for the IV argument capitalization (documentation)
isacben Mar 7, 2023
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44 changes: 30 additions & 14 deletions shared-bindings/aesio/aes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,15 +20,15 @@
//| self,
//| key: ReadableBuffer,
//| mode: int = 0,
//| iv: Optional[ReadableBuffer] = None,
//| IV: Optional[ReadableBuffer] = None,
//| segment_size: int = 8,
//| ) -> None:
//| """Create a new AES state with the given key.
//|
//| :param ~circuitpython_typing.ReadableBuffer key: A 16-, 24-, or 32-byte key
//| :param int mode: AES mode to use. One of: `MODE_ECB`, `MODE_CBC`, or
//| `MODE_CTR`
//| :param ~circuitpython_typing.ReadableBuffer iv: Initialization vector to use for CBC or CTR mode
//| :param ~circuitpython_typing.ReadableBuffer IV: Initialization vector to use for CBC or CTR mode
//|
//| Additional arguments are supported for legacy reasons.
//|
Expand Down Expand Up @@ -98,33 +98,49 @@ STATIC mp_obj_t aesio_aes_make_new(const mp_obj_type_t *type, size_t n_args,
return MP_OBJ_FROM_PTR(self);
}

STATIC mp_obj_t aesio_aes_rekey(size_t n_args, const mp_obj_t *pos_args) {
//| def rekey(
//| self,
//| key: ReadableBuffer,
//| IV: Optional[ReadableBuffer] = None,
//| ) -> None:
//| """Update the AES state with the given key.
//|
//| :param ~circuitpython_typing.ReadableBuffer key: A 16-, 24-, or 32-byte key
//| :param ~circuitpython_typing.ReadableBuffer IV: Initialization vector to use
//| for CBC or CTR mode"""
//| ...
STATIC mp_obj_t aesio_aes_rekey(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
aesio_aes_obj_t *self = MP_OBJ_TO_PTR(pos_args[0]);
enum { ARG_key, ARG_IV };
static const mp_arg_t allowed_args[] = {
{MP_QSTR_key, MP_ARG_OBJ | MP_ARG_REQUIRED, {.u_obj = MP_OBJ_NULL} },
{MP_QSTR_IV, MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
};
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

mp_buffer_info_t bufinfo;
mp_get_buffer_raise(pos_args[1], &bufinfo, MP_BUFFER_READ);

mp_get_buffer_raise(args[ARG_key].u_obj, &bufinfo, MP_BUFFER_READ);
const uint8_t *key = bufinfo.buf;
size_t key_length = bufinfo.len;
if (key == NULL) {
mp_raise_ValueError(translate("No key was specified"));
}

if ((key_length != 16) && (key_length != 24) && (key_length != 32)) {
mp_raise_ValueError(translate("Key must be 16, 24, or 32 bytes long"));
}

const uint8_t *iv = NULL;
if (n_args > 2) {
mp_get_buffer_raise(pos_args[2], &bufinfo, MP_BUFFER_READ);
size_t iv_length = bufinfo.len;
iv = (const uint8_t *)bufinfo.buf;
(void)mp_arg_validate_length(iv_length, AES_BLOCKLEN, MP_QSTR_IV);
if (args[ARG_IV].u_obj != NULL &&
mp_get_buffer(args[ARG_IV].u_obj, &bufinfo, MP_BUFFER_READ)) {
(void)mp_arg_validate_length(bufinfo.len, AES_BLOCKLEN, MP_QSTR_IV);

iv = bufinfo.buf;
}

common_hal_aesio_aes_rekey(self, key, key_length, iv);
return mp_const_none;
}

MP_DEFINE_CONST_FUN_OBJ_VAR(aesio_aes_rekey_obj, 2, aesio_aes_rekey);
MP_DEFINE_CONST_FUN_OBJ_KW(aesio_aes_rekey_obj, 1, aesio_aes_rekey);

STATIC void validate_length(aesio_aes_obj_t *self, size_t src_length,
size_t dest_length) {
Expand Down